Japanese patent application (OPI) No. 77287/1981 describes 7.beta.-(2-(2-aminothiazol-4-yl)-2-((1H-tetrazol-5-yl)methoxyimino)acetami do)-3-pyridiniomethyl-3-cephem-4-carboxylate and 7.beta.-(2-(2-aminothiazol-4-yl)-2-((imidazol-2-yl)methoxyimino)acetamido) -3-pyridiniomethyl-3-cephem-4-carboxylate, Japanese patent application (OPI) No. 139523/1979 describes 7.beta.-(2-(2-aminothiazol-4-yl)-2-((imidazol-1-yl)ethoxyimino)acetamido)- 3-acetoxymethyl-3-cephem-4-carboxylic acid (the term "OPI" as used herein refers to a "published unexamind patent application").